This stud is based upon the use of nutritional models for cataractogenesis directed toward the following objectives: 1) Identifying nutrient risk factors in cataractogenesis. 2) Evaluating the impact of nutrition on lens development. 3) Describing aspects of the biochemistry of normal and cataractous rat lens. 4) Better understanding of the relationship between lens metabolism and cataract formation. We further propose long-term experiments utilizing diets which incorporate specific nutrient deficiencies and excesses, which are known to cause cataracts, in order to assemble a high-risk cataractongenic diet. Such studies are requisite toward understanding the impact of nutrition on the serious problem of senile cataract in the human population. We propose the continued use of the defined amino acid based diets with deficiencies in tryptophan and vitamin E which we have determined to be cataractogenic for neonatal rats of dams maintained on these diets during gestation. Histology of foetal rat tissue will be employed to assess the role of these nutrients in lens development: biochemical parameters of the cataractous lens will be compared to those of normal lenses. Modification of these diets will allow identification of other nutrient factors which participate in the early appearance of cataract. Further, we intend to use similar diets, deficient in tryptophan, with weanling male rats in order to explore the impact of this deficiency on levels of metabolites and enzymes in lens during the period of catarct development, and to evaluate the occurrence and synthesis of lens crystallins, particularly betaH-crystallin, in the pre-cataractous and cataractous lens.